Fermentation lactate

Oxidative phosphorylation produces most of the ATP made in aerobic cells. Complete oxidation of a molecule of glucose to C02 yields 30 or 32 ATP (Table 19-5). By comparison, glycolysis under anaerobic conditions (lactate fermentation) yields only 2 ATP per glucose. Clearly, the evolution of oxidative phosphorylation provided a tremendous increase in the energy efficiency of catabolism. Complete oxidation to C02 of the coenzyme A derivative of palmitate (16 0), which also occurs in the mitochondrial matrix, yields 108 ATP per palmitoyl-... 

Bactofugation, a process based on centrifugal separation of bacteria and their spores, is practiced in the Netherlands. Since the spores of lactate-fermenting Clostridia (butyric acid bacteria) are removed, there is less risk that Gouda cheese will develop the late blowing defect caused by the metabolism of these bacteria (Van den Berg et al 1980). 

Combined use of lactate fermentation and ED separation has been proposed to overcome the main drawbacks of this fermentation process, that is, low microbial acidic productivity and expensive downstream processing of lactic acid fermentation broths (Boyaval et al., 1987 Hongo et al., 1986 ... 

The performance of the F-MF-ED system was also assessed in the case of lactate fermentation from xylose (Nomura et al., 1988). Starting with 50 kg of xylose per m3, the conventional or combined system allowed full exhaustion of the carbon source after 60 or 32 hours, respectively. By further increasing the initial xylose concentration to 80 kg/m3, both systems resulted in less (50 kg/m3) or more (75 kg/m3) consumption of xylose, respectively. Moreover, the simultaneous removal of microbial metabolites (lactate and acetate) via ED increased both lactate production and xylose consumption rates. 

Vonktaveesuk, P., Tonokawa, M., and Ishizaki, Y. 1994. Stimulation of the rate of L-lactate fermentation using Lactococcus lactis IO-l by periodic electrodialysis. J. Ferment. Bioeng. 77, 508-512. 

Yamamoto, K., Ishizaki, A., and Stanbury, P.F. 1993. Reduction in the length of the lag phase of /, lactate fermentation by the use of inocula from electrodialysis seed cultures. J. Ferment. Bioeng. 76, 151-152. 

It is among the most capable of invertebrate anaerobes, the helminths and the marine bivalves, that we find the best examples of alternative fermentation pathways. Many of these have been reviewed several times elsewhere, so only a brief summary will be considered here. Current concepts view the organization of anaerobic metabolism as a series of linear, and loosely linked, pathways. The most important of these, aside from classical glucose — lactate fermentation (yielding 2 moles ATP per mole glucose) are summarized by Hochachka and Somero (1984) as follows (see chapter 2) ... 

This metabolic scheme, which is called lactate fermentation, is shown in Fig. 11-7. The coreactant cycle between the two dehydrogenase enzymes, glyceraldehyde-3-phosphate dehydrogenase (Step 6) and lactate dehydrogenase, ensures that there is regeneration of NAD+ in this particular oxidation state so that glycolysis, lactate fermentation, and the production of ATP can continue. 

This, the final step in alcohol fermentation, is analogous to lactate fermentation. Both reactions regenerate NAD+ and produce low-molecular-weight, water-soluble, metabolic end products that diffuse out of the cells in which they were produced. In the case of alcoholic fermentation, the second reaction is reversible, so that if oxygen becomes available to previously anaerobic yeast cells, the ethanol is oxidized to acetaldehyde. Unlike lactate fermentation, in which the lactate is oxidized to pyruvate, alcoholic fermentation cannot form pyruvate from acetaldehyde. Instead, the acetaldehyde... 

Photosynthetic bacteria can rapidly assimilate volatile fatty acids and grow. Because it assimilates organic compounds, hydrogen production from various fatty acids has been investigated. As for volatile fatty acids, lactate obtained after lactate fermentation of carbohydrates and acetate contained in processed solution after methane fermentation can be used as a substrate. 

Little information exists on the activity of organic acids against viruses. However, enteric viruses have been shown not to possess similar susceptibility to weak organic acids compared to bacteria and consequently survive well in organic acid preserved foodstuffs such as lactate-fermented products (Adams and Nicolaides, 1997). 

In the overview of glycolysis we noted that the pyruvate produced must be used up in some way so that the pathway will continue to produce ATP. Similarly, the NADH produced by glycolysis in step 6 (see Figure 21.8) must be reoxidized at a later time, or glycolysis will grind to a halt as the available NAD+ is used up. If the cell is functioning under aerobic conditions, NADH will be reoxidized, and pyruvate will be completely oxidized by aerobic respiration. Under anaerobic conditions, however, different types of fermentation reactions accomplish these purposes. Fermentations are catabolic reactions that occur with no net oxidation. Pyruvate or an organic compound produced from pyruvate is reduced as NADH is oxidized. We will examine two types of fermentation pathways in detail lactate fermentation and alcohol fermentation. 

A variety of bacteria are able to carry out lactate fermentation under anaerobic conditions. This is of great importance in the dairy industry, because these organisms are used to produce yogurt and some cheeses. The tangy flavor of yogurt is contributed by the lactate produced by these bacteria. Unfortunately, similar organisms also cause milk to spoil. 

Under anaerobic conditions the NADH produced by glycolysis is used to reduce p)mivate to lactate in skeletal muscle (lactate fermentation) or to convert acetaldehyde to ethanol in yeast (alcohol fermentation). 

What food products are the result of lactate fermentation ... 

An enzyme that hydrolyzes ATP (an ATPase) bound to the plasma membrane of certain tumor cells has an abnormally high activity. How will this activity affect the rate of glycolysis Explain why no net oxidation occurs during anaerobic glycolysis followed by lactate fermentation. 

Both the alcohol and lactate fermentations are anaerobic reactions that use the pyruvate and re-oxidize the NADH produced in glycolysis. 

Lactate fermentation occurs in anaerobic organisms or in aerobic cells that are undergoing very high rates of glycolysis. In these cells, NADH generated in glycolysis cannot be reoxidized to NAD+. When... 

See also Anaerobic Glycolysis, Lactate Fermentation, Glycolysis, NADH, NAD+, Gluconeogenesis Precursors... 

For example, in lactate fermentation (animal cells), pyruvate is converted to lactate using the electrons of NADH, forming NAD+. Lactate is in the same oxidative state as glucose, the starting material of glycolysis. Yeast go through ethanolic fermentation for the same reason with the same result. 

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